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Topic: Lens (anatomy)


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In the News (Sat 6 Sep 08)

  
  Lens Anatomy and Types of Cataracts
The anterior side of the lens is the side exposed to the outside of the eye and the posterior side of the lens is the side inside the eyeball.
When describing the anatomy of the lens, the terms "primary lens fibers" and "secondary lens fibers" are not normally used.
The layer of cells that covers the anterior surface of the lens would then be said to be located along the anterior surface of the lens cortex.
www.dogstuff.info /lens_anatomy_kral.html   (506 words)

  
 The Crystalline Lens
The crystalline lens is composed of 4 layers, from the surface to the center:
This adjustment in lens shape, to focus at various distances, is referred to as “accommodation” or the “accommodative process” and is associated with a concurrent constriction (decrease in size) of the pupil.
Through this opening, the lens nucleus is removed, either as a whole or by dissolving it into tiny pieces and vacuuming out the pieces, a procedure called “phacoemulsification.” Next, the lens cortex also is sucked out, leaving the lens capsule in place, and into the lens capsule is inserted the artificial lens implant.
www.tedmontgomery.com /the_eye/lens.html   (3008 words)

  
 Comparative Ophthalmology Notes: Chapter 10 - Lens   (Site not responding. Last check: 2007-10-16)
This is the appearance of the lens at birth.
The defect in the lens capsule often appears as a circular defect of the lens and the protruding material may be opaque.
Lens displacement usually causes moderate iridocyclitis and, in most cases, it also causes glaucoma (presumably by impedance of aqueous flow by angle or pupillary block) with enlargement of the globe.
www.vetmed.ucdavis.edu /courses/vet_eyes/conotes/con_chapter_10.html   (4276 words)

  
 lens - Search Results - MSN Encarta
Lens (optics), in optical systems, glass or other transparent substance so shaped that it will refract the light from any object and form a real or...
Lens is the chief industrial center of a major coal basin;...
anatomy of the eye lens, animal lenses, compound eye (diagram), diseases and disorders of lens, focusing of the eye, mechanics of vision, picture...
encarta.msn.com /encnet/refpages/search.aspx?q=lens   (178 words)

  
 Lens Anatomy
The central compactly arranged fibers of the lens form the 'nucleus', while the periphery is called the cortex.
Accordingly the lens capsule becomes taut or relaxes, thus changing the thickness of the lens, thus, the eye becomes focused for distance or near.
The elasticity of the lens capsule is lost with aging, thus causing presbyopia.
members.tripod.com /manisha_b/Cataract/Lens.htm   (150 words)

  
 Eye Vet - Zigler Veterinary Professional Corporation
The lens of the eye is the clear structure which focuses the image onto the retina.
When lens luxation occurs secondarily to glaucoma, it usually occurs late in the disease once the elevated pressure within the eye has caused the sclera to stretch, and the zonular ligaments to tear.
If the lens luxation is recent, and if the glaucoma is not severe, and the retina and optic disc still look healthy, then there may be a reasonable chance of saving vision with surgery.
www.eyevet.info /luxlens.html   (1311 words)

  
 Lens - Wikipedia, the free encyclopedia
Photographic lens, a special type of lens used in a camera.
Lens (genus), the genus of the lentil plant
Lens (geology), a body of ore or rock that is thick in the middle and thin at the edges
en.wikipedia.org /wiki/Lens   (160 words)

  
 Lens (anatomy) - Wikipedia, the free encyclopedia
The lens or crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to focus on the retina.
The lens gradually loses its accommodation ability as the individual ages, the loss of the individual's focusing ability is termed Presbyopia.
During the fetal stage, the development of the lens is aided by the hyaloid artery.
en.wikipedia.org /wiki/Lens_(anatomy)   (426 words)

  
 Gray, Henry. 1918. Anatomy of the Human Body. Page 1019
—The crystalline lens, enclosed in its capsule, is situated immediately behind the iris, in front of the vitreous body, and encircled by the ciliary processes, which slightly overlap its margin.
The capsule of the lens (capsula lentis) is a transparent, structureless membrane which closely surrounds the lens, and is thicker in front than behind.
The lens is a transparent, biconvex body, the convexity of its anterior being less than that of its posterior surface.
www.bartleby.com /107/pages/page1019.html   (261 words)

  
 eMedicine - Myopia, Phakic IOL : Article by Arun Verma, MD   (Site not responding. Last check: 2007-10-16)
An iris claw lens is attached to the peripheral anterior surface of the iris by pushing a fold of the iris into the 2 claws of the lens.
The haptic of the lens in the periphery is 0.18 mm.
Friction between the iris claw lens and the anterior surface of the iris is possible at the immediate vicinity of the 2 claws as well as along the edge of the lens.
www.emedicine.com /oph/topic668.htm   (10560 words)

  
 Olympus Microscopy Resource Center: Anatomy of the Microscope - Magnification   (Site not responding. Last check: 2007-10-16)
A simple microscope or magnifying glass (lens) produces an image of the object upon which the microscope or magnifying glass is focused.
The magnification of an infinity-corrected objective equals the focal length of the tube lens (for Olympus equipment this is 180mm, Nikon uses a focal length of 200mm; other manufacturers use other focal lengths) divided by the focal length of the objective lens in use.
The first lens of a microscope is the one closest to the object being examined and, for this reason, is called the objective.
www.olympusmicro.com /primer/anatomy/magnification.html   (2976 words)

  
 Olympus Microscopy Resource Center: Anatomy of the Microscope - Java Tutorials   (Site not responding. Last check: 2007-10-16)
Perfect Lens Characteristics - The simplest imaging element in an optical microscope is a perfect lens, which is an ideally corrected glass element that is free of aberration and focuses light onto a single point.
In such a microscope, magnification of the intermediate image is determined by the ratio of the focal lengths of the tube lens and objective lens.
Depending on the angle of the off-axis rays entering the lens, the line image may be oriented in either of two different directions, tangentially (meridionally) or sagittally (equatorially).
www.olympusmicro.com /primer/anatomy/anatomyjava.html   (2264 words)

  
 Welcome to 20/20 Online   (Site not responding. Last check: 2007-10-16)
With any soft-toric lens, lens rotation on the eye is the biggest hindrance to visual success, as this changes the astigmatic prescription of the lens while being worn.
Lens rotation may be a result of lid interaction with a lens edge, otherwise poorly fit lenses or simply secondary to lens dehydration (dry eyes, dry environs, lengthy wear times, etc.).
To reduce the effect of soft-toric lens rotation, it is best to choose refractive prescriptions where the spherical component of the Rx is proportionately three to four times the power of the refractive astigmatism (i.e.,-4.00D -1.00D by 170 is a good visual candidate while -1.00D -1.75D by 175 may be unhappy).
www.2020mag.com /ce_article.asp?page=ce/2628/lesson.htm   (2260 words)

  
 96 Specialty   (Site not responding. Last check: 2007-10-16)
The predominant eye problem in the breed and at the clinic % was cataracts, so I have prepared a section on lens anatomy and terminology used to describe these abnormalities to accompany a description of the problem.
The lens itself is made up of tiny lens fibers, which are arranged in layers, like an onion or tree rings.
The fibers you are born with (the center of the lens) is termed the nucleus.
www.beaconforhealth.org /CERF-Specialty.htm   (1066 words)

  
 Lens - eye anatomy
The nucleus, the innermost part of the lens, is surrounded by softer material called the cortex.
The lens is encased in a capsular-like bag and suspended within the eye by tiny "guy wires" called zonules.
With age, the lens gradually hardens, diminishing the ability to accommodate.
www.stlukeseye.com /anatomy/Lens.asp   (90 words)

  
 Eye Anatomy: Lens and Ciliary Body
The lens is a completely clear, fairly flat sphere inside your eye used to focus light to a point, called the macula (where your center of vision is), in the back of your eye.
Damage to the lens is irreversible and cannot be repaired, but only replaced by an implant lens.
The ciliary body is a muscle structure around the lens that constrict to pull on the ligaments and fatten the lens so we can see close up.
library.thinkquest.org /C005949/anatomy/lensciliary2.htm   (275 words)

  
 Wiley X | Outdoors Eyewear - Lens Anatomy
Lens Technology: Our lenses are meticulously designed with pure shatterproof selenite polycarbonate to protect your eyes from anything that may be hurled in your direction.
Each lens is formulated and die-cut to eliminate distortion, creating perfect optical clarity and reducing eyestrain.
This blended lens of Neutral Slate and Vermillion hues provides excellent contrast of orange targets against a blue sky or green to brown background.
www.wileyx.com /outdoors/outdoors_anatomy.aspx?ActivityCode=OUTDOORS   (670 words)

  
 Anatomy of the Eye   (Site not responding. Last check: 2007-10-16)
The lens is responsible for focusing light onto the retina.
As we age, the lens becomes less flexible and able to "accommodate" or change focus.
When the cataract becomes dense enough to interfere with vision, it can be replaced with a clear artificial lens implant during cataract surgery.
www.vrmny.com /anatomy.htm   (893 words)

  
 Wiley X 900 Rebel sunglasses in Black at eyeglasses.com   (Site not responding. Last check: 2007-10-16)
We then formulate and die cut each lens to the maximum density and thickness creating one of the strongest lenses available, while still maintaining distortion free clarity.
Overall it is the most suitable lens color to sharpen and enhance ground level contours.
It is a versatile lens, and a good choice for golfing, biking, hiking, sport shooting, and driving.
www.eyeglasses.com /product/1012320832-1012320832   (627 words)

  
 The Anatomy of a Lens
The fact that a double convex lens is thicker across its middle is an indicator that it will converge rays of light which travel parallel to its principal axis.
The fact that a double concave lens is thinner across its middle is an indicator that it will diverge rays of light which travel parallel to its principal axis.
If a symmetrical lens is thought of as being a slice of a sphere, then there would be a line passing through the center of the sphere and attaching to the mirror in the exact center of the lens.
www.glenbrook.k12.il.us /gbssci/phys/Class/refrn/u14l5a.html   (760 words)

  
 Eye Anatomy & Physiology - VisionChannel
The lens focuses light rays onto the retina by bending (refracting) them.
Behind the lens and in front of the retina is a chamber called the vitreous body, which contains a clear, gelatinous fluid called vitreous humor.
Aqueous humor is nutritive watery fluid produced by the ciliary body through the ciliary body processes and secreted into the posterior chamber (i.e., space between the iris and the lens).
www.visionchannel.net /anatomy.shtml   (978 words)

  
 Ocular Anatomy for medical students and primary care physicians
Keratometry mesures the average corneal curvature of the central 3mm along the vertical and horizontal meridians.Clinically used to calculate the power of the IOL(intraocular lens) needed to replace the cataractous one being extracted.
Contraction of the longitudinal muscle stretches mainly the choroid but also applies forces on the scleral spur thereby opening the canal of schlemn and facilitating the aqueous drainage.Pilocarpine is a cholinergic drug clinically used to decrease intraocular pressure in glaucoma patients, by the above mechanism.
Occlusion of these vessels and infarction of the nerve causes AION (anterior ischemic optic neuropathy).The patient presents with sudden and painless loss of vision,mostly an altitudinal defect affecting the inferior visual field.
www.eyeweb.org /anatomy.htm   (2590 words)

  
 The Lens
It is attached to the ciliary muscle which changes the shape of the lens.
The change of the shape of the lens is accommodation.
Relaxed The change of the shape of the lens is accommodation.
retina.anatomy.upenn.edu /~lance/eye/lens.html   (467 words)

  
 Anatomy
If a new lens is not implanted, then very thick converging-lens glasses are needed to bring images to a focus on the retina.
When you look at an object, your eye moves to image each part of the object in turn on the fovea where fine detail can be seen.
The lens grows throughout life until, at around age 45, the focusing muscles become ineffective.
www.people.vcu.edu /~rgowdy/mod/109/xmp.htm   (179 words)

  
 A Big Look at the Eye
The lens sits behind the iris and is clear and colorless.
The lens' job is to focus light rays on the back of the eyeball — a part called the retina (say: reh-tin-uh).
The lens is suspended in the eye by a bunch of fibers.
kidshealth.org /kid/body/eye_noSW.html   (1746 words)

  
 eye anatomy
The anterior chamber is the area bounded in front by the cornea and in back by the lens, and filled with aqueous.
The cornea is a clear, transparent portion of the outer coat of the eyeball through which light passes to the lens.
The posterior chamber is the area behind the iris, but in front of the lens, that is filled with aqueous.
www.discoveryfund.org /anatomyoftheeye.html   (391 words)

  
 eMedicine - Myopia, Clear Lens Extraction : Article by Mounir Bashour, MD, CM, PhD, FRCSC, FACS
Clear lens extraction (CLE), also called refractive lens exchange (RLE), is the removal of a noncataractous natural lens of the eye with or without intraocular lens placement as a refractive procedure.
Optical or refractive indications for lens surgery are ametropia (ie, myopia, hyperopia, astigmatism), anisometropia, and presbyopia.
Relevant Anatomy: CLE is performed as any other cataract procedure; the only difference is the decreased use or absence of phacoemulsification power and the almost exclusive use of aspiration.
www.emedicine.com /oph/topic664.htm   (2783 words)

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